Canada’s highest court has left many questions for some of the central players in any future assisted death scheme — the very doctors who will be asked to help put to death adults who have decided life is no longer worth living.

What is “grievous” suffering? Who defines it? What form of “physician-assisted death” would be permitted? Death by a lethal prescription the patient would take herself, or death by lethal injection? Would physicians opposed to medical aid in dying have the right to refuse to even refer a patient seeking assisted death to another doctor willing to perform it?

“We can’t just simply say we’re going to compel physicians to do things that they personally, morally and ethically can’t do,” Dr. Chris Simpson, president of the Canadian Medical Association said in an interview from Yellowknife moments after the historic and unanimous ruling was released in Ottawa. “But at the same time I think we have to respect that society now has a different view on this. . . . The Supreme Court of Canada has ruled patients have a right to equitable access (to doctor-hastened death) and it’s up to us to figure out how to achieve that.”

In its historic and unanimous ruling, the Supreme Court said it would be up to physicians’ colleges, Parliament and the provincial legislatures to craft a comprehensive assisted death regimen for people experiencing physical or psychological suffering. The court, however, didn’t say whether it would apply to people with mental illness such as depression.

But it did set out some parameters. First, assisted dying would be permitted for competent adults only who could explicitly provide consent — and not people who have been delegated their substitute decision makers should they ever lose the capacity to speak for themselves. “That would appear to set aside concerns of substitute decision makers making the decisions for patients who don’t have competence,” said Simpson, a cardiologist and chief of cardiology at Queen’s University in Kingston, Ont.

The patient would also have to have a “grievous and irremediable medical condition” causing “enduring suffering that is intolerable to the individual in the circumstances of his or her condition.”

The court defines a medical condition as an “illness, disease or disability.” But it did not say specifically which conditions would qualify, or where in the course of the illness the person would have to be.

The word “grievous” might also be problematic, said University of Ottawa law professor Amir Attaran. “Grievous is in the eyes of the beholder,” he said.

“The person says, ‘I find this intolerable and I am choosing death over the grievous pain I am feeling.’ Nobody much can define that other than the person who is experiencing it.

“Irremediable is a tougher call. Does that mean an untreatable condition? I think it probably does.”

The person’s condition doesn’t need to be terminal and the court said doctors should be capable of assessing whether someone is competent, and that proper safeguards would protect the vulnerable from “abuse or error.”

The court said declaring the current prohibition against assisted dying constitutionally invalid doesn’t mean doctors would be compelled to provide aid in dying. A doctor’s decision to participate “is a matter of conscience and, in some cases, of religious belief,” the court wrote. But it was more circumspect on whether doctors would be compelled to refer patients to other providers, noting that the charter rights of patients and doctors “will need to be reconciled.”

Doctors are far more deeply divided on assisted suicide than the general public, Simpson said, “and we’ll be looking really carefully for language that protects individual doctors’ right to conscientiously object, and not participate. My early feeling is that there is a lot of reassuring language on that,” he said.

Simpson said the number of patients who would likely be eligible for, or even request assisted death, would be so small, based on experience in other jurisdictions, that there would be sufficient numbers of doctors to provide equitable access for all, “without compelling a large number of doctors to personally participate.” The CMA’s own internal polling suggest about a quarter of doctors in Canada would be willing to help a patient die.

“We need to have a system that balances the right of physicians not to participate, and perhaps not even to refer, but that has to be done in a way that doesn’t impair access for patients who would qualify for this,” Simpson said.

Whatever the final parameters — including what medications would be used, how many doctors would be required, who would have to witness and document assisted deaths — the ruling will provide comfort to Canadians seeking a “humane and dignified” exit from this world, and in their own country, says the family of the woman behind the original lawsuit.

Kathleen (Katy) Carter, of B.C., died five years ago on January in a Zurich clinic, after ingesting a lethal dose of barbiturates. “It was a beautiful death, if that’s possible, for someone who wanted to go,” her daughter Lee told Postmedia News.

Katy Carter’s body was deteriorating rapidly from a painful and paralyzing spinal condition when she died in January 2010, at age 89, surrounded by her family.

Before she died, her mother was unable to go to the toilet on her own, “ to get up, or to do anything herself,” Lee said. “After two-and-a-half years of that she said, ‘I want out. I’ve had a good life, and it’s time for me to go. Lee, will you help me go to Switzerland?” her daughter recalls.

Katy Carter died in her children’s arms. “She literally died with a smile on her face,” Lee’s husband Hollis said.